Roller ring mill



Feb. 16, 1965 s. SCHAUER ETAL 3,169,712

ROLLER RING MILL Filed July 16, 1962 3 Sheets-Sheet 1 Feb. 16, 1965 s. SCHAUER ETAL 3,169,712

ROLLER RING MILL Filed July 16, 1962 3 Sheets-Sheet 3 United States Patent Q The present invention relates to mills, particularly roller ring or roller drum mills, and more especially the shape of the housing and of the pressure ring for such mills or equivalent structures. A mill of the type to which the invention is applicable is described in US. Patent No. 3,061,208; I

' In mills of this type a grinding drum rotatesin a housing about a vertical axis. The ground material is whirled about and carried along by an air stream which sweeps through the housing. Heretoforethe milling elements circulating about the vertical central axis as well as the circulating air stream made it a requisite to construct the housing with a circular crosssection, i.e. cylindrically, conically or the like; In such a housing with-a curved surface necessarily the design of lateral'passages, control apertures, seals, the arrangement of the internal components, particularly the yoke for mounting the wear or friction plates which serve for guiding the pressure ring, etc., involves enormous diificulties.

Accordingly it is proposed in accordance with the invention to construct the housing of mills of this type or of similar structures no longer circular but in the form of a multi-cornered prism-which is symmetric with respect to the center axis, and it has been foundin practice that the most advantageous form is one of hexagonal cross section.

The angular construction of the housing provides for flat housing surfaces in which the necessary apertures'for passages and other componentscan be accommodated without difficulties.

Moreover, the angular design of the mill provides a surprising advantage as far as the function of the mill or grinder is concerned. The housing ofmi-lls of this type connects at the top with a hood in which a sitter is installed. Circumferentially of the grinding drum a ring of nozzles is arranged through which air is blown in. The air space carries a stream of material upwardly from the roller drum to the sitter, whichcontains a quantity of incompletely ground material which is several times as great as the'quantity of the finishedproduct. The work of the sifter is therefore considerably more difiicult. The angular construction of the housing by way of the corners provides for a pre-separation of the incompletely ground coarse grain from the material carried upwardly by the air current. Thus the resulting pre-separation provides for easing the load on the sitter. As far as the technical problem posed by the air is concerned, a considerable saving of power is obtained.

Furthermore, the improvement of the control or guidance of the pressure ring made possible by the angular design is of particular importance.

In mills of this type the pressure ring must be guided in the housing, and conventionally that iseftected by three rather strong yokes to which the wear plates which are engaged by the pressure ring are secured. The efiiciency of the transmission of the moments by way of these yokes to the housing of the mill is quite poor, so that the housing which is conventionally of circular cylindrical form is subjected to considerable forces which result at least in temporary distortions of the housing. Moreover, the mounting of the wear plates is cumbersome, and rapid replacement or exchanging thereof is not possible.

3,169,712 Patented: Feb. 16, 1965 In the angular housing in accordance with the invention the Wear plates can be arranged in the stiff corner: regions of the housing directly on the inner wall, while the pressure ring is provided with guiding members which cooperate directly with the wear plates. Preferably these guiding members and the pressure ring-can be in the form of a unitary structure. Further advantages and objects of the invention will become apparent'from an embodiment of the invention which is schematicallyillustrated in the accompanying drawings that show the mill housing which is preferably of hexagonal cross section wherein the wear disks or plates are provided inthree corners-of the hexagonal housing which are symmetrically disposed rela. tive to one another. In the drawing:

FIG. 1 is a perspective view of the mill;

FIG. la is a section th'roughthe mill shown in FIG. 1 taken along line IVIV in FIG. 3;

FIG. 2 is a horizontal section through-themill housing taken approximately along the line II--II in FIG; 1

FIG. 3 shows the top viewof the pressure ring and-of the adjacent components of the mill, and

FIG. 4 is a section taken alongthe lineTV1V in FIG. 3. I

The mill or grinder illustrated is of the roller ring or drum roller'mill type. The grinding rollers 1 run upon a roller drum or grinding plate In which rotates about the vertical center axis while the platelet is rotated in the conventional manner.. Circumferentially of the grinding plate a nozzle ring (not illustrated) for blowing in air is provided. The streamof air is indicated byarrows 2 in the housing andmoves upwardly with the ground material which it picks up and carries along. The mill is closedat the top by means of a hood 10 in which a sitter: orseparating screen ltta is provided, which takes care of the o separating of the completely ground material thatis 'to be discharged out of the upwardly guided mixture of air, coarsely ground and finely ground material.

The housing of the mill has numerous apertures such as entrance gates, passage apertures, materialteedopenings and the like which have to be well sealed. In addition a series of built in components is needed, such as supporting means for the roller ring, etc., which partly must be passed through and out of the housing. In this connection the guiding of the pressure ring is of particular significance. As required by the symmetry of rotation of the grinding mechanism, the housings of such mills were heretofore constructed in the form'of rotational bodies conforming to the symmetry of rotation, such as conventional cylinders having a circular cross section or the like.

Contrary to this form of construction, the housing in accordance with the inventionis constructed as a-pri'srn that is symmetric with respect to the vertical center axis, In the embodiment illustrated the mill housing 3 is of hexagonal cross section. Thusithas sixplane wall portions 4 which abut in six corners 5: It is possible without structural complications to provide in these plane wall portions gates 6, coverings 7 for the roller ringsuppo-rts and the like. The housing 3 extends downwardly to a base 8 which is likewise of hexagonal form, and upwardly by way of a flange 9 it merges with an intermediate member 9'which continues on into a round hood-1t) for the sifter. Owing to the shape of the housing 3 the intermediate member 9 presents also plane surfaces so that 5 the apertures necessary there may likewise be of structurally simple form, for example, for the material entrance 11.

In FIGS. 1 and 2 there is also shown a drive means 12 for the roller drum or grinding plate 1a and a drive means 13 for the sifter.

In the conventional round mill housings in accordance in mill housings of angular cross section. It has been found, however, that a much simpler and better form can be obtained if the advantages provided by anangular mill housing are utilized. In accordance with the invention the said yokes can be eliminated. Merely wear plates 15 are provided in the regions ofcorners or in a chosen number of them in the mill housing 3 directly upon the inner wall thereof. In the chosen embodiment such Wear plates are arranged along three corners S of the hexagonal mill housing 3 at the level of the pressure ring 14. Guide members 16, are'provided on the pressure ring 14 which can be readily adapted there to by way of which the pressure ring 14 is guided on the wear plates 15. The pressure ring 14 together with these guide members 16 is preferably made as a unitary structure. a t

In addition to the very extensive simplification of the structural details afforded by the angular construction of the housing, substantially enhanced effects are obtained for the operation of the mill., As already mentioned, the material introduced and to be Worked in the mill is guided upwardly by a circulating air current to the sitter 10a, and in the round housing the proportion of incompletely ground material greatly exceeded the proportion of the finished product that had to be separated by the sif ter, so that the operation :of the sitter and of the feeding by means of the air stream involved considerable power consumption. With the angular, for example, hexagonal construction of the housing the coarse product carried along in the air current is separated to a large extent in the corners of the housing'and returns again to the grinding drum, while in practice only the finely ground material reaches the sifter at the top. Thus a substantial advantage is obtained with respect to the mechanical operating techniques, which is combined with an equally substantial saving in power as far as the air operating techniques of the mill operation are concerned. Furthermore, the embodiment in accordance with the invention aifords that the housing, which provides inherently more resistance against bending factors or other damage than a round cylinder, is only stressed along its stifiest areas such as the corner regions due to the guidance of the pressure ring. Furthermore, the arrangement and the exchanging of the wear plates provide no difficulties whatsoever and may be effected very rapidly. Finally, the conventional strong support yokes whichwere heretofore required can be eliminated. .It is understood, of course,'that if it should appear 'to be necessary for any reason whatsoever, that the pressure ring can also be supported in all corners of the hexagonal mill housing. Finally the same support is also possible in angular housings of different cross section than hexagonal, while again the supporting may be obtained at all corners or in a selected or predetermined number of corners.

Having now described our invention with reference to the embodiment illustrated in the drawings, we do 'not wish to be limited thereto, but what we desire to protected by Letters Patent of the United States of America is set forth in the appended claims.

We claim: a

1. A roller mill of the type having a housing, a grinding plate disposedrin said housing ,for rotation about 'a vertical axis, roller supporting means, rotatable milling or grinding elements, particularly rollers rotatably supported over said grinding plate by said supporting-means, and a sifting device disposed in said housing above said grinding elements, said housing being in the form of a multi-angular prism disposed symmetrically with respect to said vertical axis and defining angular corners providing support later-ally of said supporting means.

2. A roller mill of the type having a housing, a grinding plate disposed in said housing for rotation about a vertical.

axis, roller supporting means, rotatable milling or grinding elements, particularly rollers rotatably supported over said grinding plate by said supporting means, and a sifting device disposed in said housing above said grinding elements, said housing being in the form of a hexagonal prism disposed symmetrically with respect to said vertical axis and said roller supporting means having configurations in supporting engagement with adjacent sides of said prism. I I

3. A roller mill of the type having a housing, a grinding plate disposed in said housing for rotation about a vertical axis, roller supporting means, rotatable milling or grinding elements, particularly rollers rotatably supported over said grinding plate by said supporting means, and

.a sifting device disposed insaid housing above said grinding elements, said housing being in the'form of a multiangular prism disposed symmetrically with respect to said vertical axis and defining angular corners, said roller supporting means comprising a pressure ring disposed above said rollers, said housing supporting a plurality of Wear resistant plates adjacent a plurality of said angular corners and said ring having radially extending guide members forming unitary structure with said ring and being slidable on said wear plates. i I

4. A roller mill of the type having a housing, .a grinding plate disposed in said housing for rotation about a vertical axis, roller supporting means, rotatable milling or grinding elements, particularly rollers rotatably supported over said grinding plate by said supporting means,

and a sifting device disposed in said housingabove said References Cited by the Examiner V UNITED STATES PATENTS 3,061,208 10/62 Schauer etal 241-117 FOREIGN PATENTS 902,573 1/54 Germany.

288,931 9/31 Italy.

I. SPENCER OVERHOLSER, Primary Examiner. 

2. A ROLLER MILL OF THE TYPE HAVING A HOUSING, A GRINDING PLATE DISPOSED IN SAID HOUSING FOR ROTATION ABOUT A VERTICAL AXIS, ROLLER SUPPORTING MEANS, ROTATABLE MILLING OR GRINDING ELEMENTS, PARTICULARLY ROLLERS ROTATABLY SUPPORTED OVER SAID GRINDING PLATE BY SAID SUPPORTING MEANS, AND A SIFTING DEVICE DISPOSED IN SAID HOUSING ABOVE SAID GRINDING ELEMENTS, SAID HOUSING BEING IN THE FORM OF A HEXAGONAL PRISM DISPOSED SYMMETRICALLY WITH RESPECT TO SAID VERTICAL AXIS AND SAID ROLLER SUPPORTING MEANS HAVING CONFIGURATIONS IN SUPPORTING ENGAGEMENT WITH ADJACENT SIDES OF SAID PRISM. 